iPad I have an iPad Air on 12.1.1 and want to jb. What should I do?

[iRock1]

First of all I don't think this is a low-effort post. I've done a quick read and still have doubts.

The thing is I've been far from the jb scene for a long time. Now I want to jb my iPad Air, but I see there are two methods: chimera and unc0ver.

First question: which one is better and why?

Second: should I update to 12.4 and then jb? I have my blobs saved anyway.

Thanks a lot in advance!